Before attempting any changes to a database's structure (schema or physical design), what complete set of preparatory actions should be taken to minimize risk and ensure recoverability and correctness?

Introduction / Context:
Safe database change management requires planning, validation, and rollback readiness. Even a small structural change (for example, adding a constraint or altering a column type) can impact applications, data quality, and availability. This question asks for the full set of prudent, professional actions to perform before making any database structural modifications.

Given Data / Assumptions:

• You plan to change schema objects such as tables, indexes, constraints, or triggers.
• The database contains production data that must be protected.
• You have access to a non-production environment for testing.

Concept / Approach:

Best practice combines three pillars: understanding, testing, and backup. First, thoroughly understand the current schema and data so you can predict side effects. Second, test proposed changes in a separate test or staging database to confirm behavior and performance. Third, take a full, restorable backup of the production database so you can recover quickly if something goes wrong.

Step-by-Step Solution:

Verification / Alternative check:

Perform a trial recovery from the backup in a sandbox. Validate that the restored database is consistent and applications can connect. This confirms that the backup truly protects you.

Why Other Options Are Wrong:

Option A: Understanding alone is insufficient without testing and backups.

Option B: Testing without understanding or backup still risks production impact.

Option C: A backup alone prevents data loss but does not ensure correctness or performance of the change.

Common Pitfalls:

Skipping test rehearsals, assuming a backup is valid without restore testing, and overlooking dependencies such as views, ETL jobs, or app code that rely on the old schema.

Final Answer:

All of the above should be done.